Manufacturing method and apparatus



Aug. 15, 1961 R. R. DE AMIC IS ET AL MANUFACTURING METHOD AND APPARATUS 2 Sheets-Sheet 1 Filed Oct. 9, 1959 km w wk Gk NN 1N VEN TORS Redenfo R De/Jm/c/s BY Nlcholas A. Mussel/0 W A W a 5 is Aug. 15, 1961 R. R. DE AMlClS ET AL 2,996,167

MANUFACTURING METHOD AND APPARATUS 2 Sheets-Sheet 2- Filed. Oct. 9, 1959 United States Patent Ofice 2,996,167. Patented Aug. 15, 1961- 2,996,167 MANUFACTURING METHOD AND APPARATUS Redento R. De Amicis, Glen Ellyn, and 'Nicholas A. Massello, La Grange Park, Ill., assignors to General Electric Company, a corporation of New York Filed Oct. 9, 1959, Ser. No. 845,473 6 Claims. (Cl. 198-19) This invention relates to manufacturing processes and equipment, and in particular to a method of manufacture whereby objects which are generally similar in shape but varying in a common basic dimension may be worked on in a multi-stage machine without the necessity of making a new machine set-up to accommodate the difference in said dimension.

As a typical, but not restrictive, example of the utility of our invention, we cite the preparation of domestic refrigeration doors for the application of hinges thereto. Domestic refrigerators are made in various models in which the door size may diifer from model to model. For example, a large, single door refrigerator may have a door in which the hinges, located at opposite ends of the door, are spaced apart approximately 64 inches; a two door combination refrigerator and freezer may use a. relatively small freezer compartment door having hinges spaced approximately 14 inches apart and a larger door for the fresh food compartment which is, nevertheless, considerably smaller than the full size door of the one-door model. The manufacturers models may also include smaller, single door refrigerators having correspondingly less hinge spacing.

As is well known in refrigerator manufacturing, it is not always possible to schedule long runs of any one door size; whereupon under conventional manufacturing methods, it has been necessary to interrupt production while skilled setup men adjusted the machine to accommodate the conditions of the next door size. The nonproductive time thus spent is very substantial, and when relatively few of the new sizes are to be run, the down time imposes a high burden on the manufacturing cost.

It is, therefore, an object of the invention to provide a manufacturing method and apparatus pursuant to which structures of similar shape, but differing in a common, basic dimension, may be worked on at portions of the structure having a common relation to the basic dimension without requiring any adjustment of the apparatus to conform to the said dimensional differences.

It is another object of the invention to provide a method of operation whereby door structures having varying distances between hinge locations can be prepared to receive the hinges on apparatus which will accept any mixture of door sizes without interruption of production.

In a typical embodiment of the invention the method comprises loading articles such as refrigerator doors at the receiving end of a first machine section which includes a series of spaced work stations, at each of which is apparatus performing a necessary operation to form and prepare the door for the attachment of a hinge. By conventional timed mechanism, the doors at the respective stations are advanced one station after an interval represented by the time required to perform the most lengthy of the individual operations. The final station in the first machine section is an idle station at which the doors are successively positioned for lateral transfer to a second machine section arranged in a parallel offset relation to the first section. By suitable transfer mechanism, the door is laterally shifted to a combination transfer and first operation station at the new machine section at which the first of the operations at the opposite door hinge location is performed. Similar equip- ;ment is provided at the second machine section to advance the door to the successive work stations, at which may be performed operations which may be identical with those of the first machine section, or such other operations as are appropriate.

It will be seen, therefore, that our improved method contemplates performing the necessary operations at one end of the basic dimensions of the object-in the selected example, this means conducting the necessary operations in succession at one hinge location-and then transferring the door laterally to a co-ordinated machine at which the same or other operations are performed at the opposite hinge location. At each machine station the operations are arranged along a line parallel to the direction of movement of the doors. The lateral spacing between the line of operations of the respective first and second machine sections is preferably slightly greater than the length of the hinge wall or corresponding basic dimension of the longest of the doors. By suitable means responsive to the door coming into proper operational registry with the second line of operating stations, the movement of the transfer mechanism is interrupted, and the mechanism returns to a home position, ready to receive the immediately succeeding door. It will thus be understood that the transfer mechanism will always effect the proper movement to bring any mixture of door sizes from the line of the operating stations of the first machine section to the line of operating stations of the second machine section.

Other features and advantages of the invention will be understood by the following detailed description of an embodiment thereof read in connection with the ac companying drawings in which:

FIGURE 1 is a somewhat schematic plan view of the first and second mac 'ne sections; the second section being shown only fragmentarily;

FIGURE 2 is a side elevation of a portion of the second machine section with certain 1 elements thereof broken away to reveal underlying structure;

FIGURE 3 is an end elevation of the first machine section taken on the lines 3v-2*a of FIGURE 1 and representing the positioning of a refrigerator door for lateral transfer to the first operation station of the second machine section;

FIGURE 4 is a schematic layout of the hydraulic system for the elevator and carriage shifting mechanism;

FIGURE 5 is a schematic control cycle diagram for operating the hydraulic system control valves in timed sequence; and

FIGURE 6 is a schematic circuit for the operation of the transfer mechanism.

FIGURE 1 is a somewhat schematic plan view of apparatus for practicing the present invention in connection with the manufacture of refrigerator doors to which top and bottom hinges are to be applied. Pursuant to the manufacturing method, the machine comprises a first section 1 and a second section 1a; said machine sections are substantial duplicates, and components of the second section which are duplicates of the first sec tion will be identified by means of the reference character of the first section with the subscript letter a. Section 1 of the apparatus includes a loading station 2, a plurality of work stations 3, 4, 5, and an idle station 6, which the doors reach in preparation for transfer to the second machine section. Station 6 will therefore be called the transfer station. At the loading station and at each of the work stations, means are provided to support the work, which is respectively identified in the respective sizes by the letters A, B, and C. At the loading station the supporting means comprises a table-like structure comprising components 7 and 8 extending upwardly from the machine base 10 and a support arm 11 extending cantilever fashion from a suitable pedestal secured to the base '10. Similarly,

work station 3 comprises a table 12 and a support arm 14; work station 4 includes a table 15 and a support arm 16; work station includes a work table 17 and a support arm 18. Transferstation 6 includes a pair of support members 20, 21 which are angle irons with the respective flanges 22, 23 extending upwardly. Said flanges are spaced apart sufficiently to slidably engage the outer side walls of a door structure (not shown) which is placed upon the respective support members as later described. The transfer station also includes the support arm 24 similar to the several support arms 11, 14, 16 and 18 of the preceding stations. Each of the table structures has shoulders or abutments (not shown) which are received inside of the door structures at the corners thereof as the doors are placed thereon. Each of the support arms has spaced shoulders, see, for example, the shoulders 25, 26 of support arm 14 against which the transverse wall of a refrigerator door rests when the door is in position at a work station. It will be understood that the respective shoulders 25 and 26 are located with respect to the abutments (not shown) at the work stations to accommodate the longest door A and the intermediate length door C. The size of the smallest door B is such that it can be adequately supported at the respective work tables without the necessity of supplemental support means.

It will be assumed that at each of the hinge positions the doors are to be annealed, embossed and pierced. The annealing takes place at work station 3, at which is located a gas fueled burner head 23 from which gas flames impinge against the corner of the refrigerator door. As illustrated, a size B door is undergoing treatment. At station 4 a conventional hydraulically operated embossing press 30 is operating upon the corner of an intermediate size door C.

At station 5 a hydraulically operated reciprocating piercing tool 31-is operating on a refrigerator door also of theintermediate size C. It will be understood that the designated tools are timed in their operational sequence by conventional means (not shown) suchas the familiar hydraulic tool timing systems.

FIGURE 2 shows in schematic form a method of transporting the work from one station to the next. The figure is a representation of a portion of machine section 1a and it will be understood that the direction of movement of the work is toward the right of the figure. The mechanism operates to lift the work from the support arms and work tables, move the work longitudinally, and then lower it to the next set of support arms on the work tables, following which the transport carriage returns to a home position. As illustrated, the elevator mechanism for the machine section 1a, designated 32a, comprises. an elongated platform 33a arranged to be raised and lowered by any suitable means, such as a hydraulic cylinder 34a of which there may be one or more depending upon the required length of the platform 33a. Each cylinder has a piston rod 35a operating on the platform by means of the transverse structural members 36a. A suitable plurality of rollers 37a is mounted on the platform. 33a to slideably support the work-advance carriage 40a.

Carriage 40a (see FIGURES l and 2) comprises structure including the longitudinal side rails 41a, 42a joined by the X-shaped frame work 43a for rigidity. The side rails are supported on the rollers 37a whereupon it is apparent that the carriage 40a may be shifted longitudinally relative to the elevator 32a. A hydraulically operated shifting mechanism is shown in FIGURE 2, in which both the elevator and the carriage are shown in the position they occupy when work is being performed on the doors. In other words, both the elevator and the carriage are in a home position. The carriage shifting mechanism has been somewhat schematically shown as comprising a hydraulic cylinder 44a, the piston rod 45a of which is operationally associated with a shift lever 46a pivotally supported in the base of the machine section. The connection of the piston rod with the shift lever may be by means of a suitable clevis or equivalent 3911 which accommodates the rectilinear movement of the piston and the arcuate movement of the lever 46a. Lever 46a terminates at a collar 47a which rides freely on a shaft 48a extending vertically from a transverse member 49a fixed to the carriage. It will be apparent that as the piston rod 45a is drawn to the right, the lever 46a and its associated collar 47a will enforce a movement of the entire carriage in a rightward direction. The stroke of the hydraulic cylinder system accomplishes a rightward carriage movement exactly suficient to advance the work from one station to the next.

The elevator and the carriage described immediately above are identical to that of the first machine section and the structural parts common to the two mechanisms have identical reference characters except for the subscript letter appearing with respect to the second machine section.

The two machine sections differ essentially only as required for effecting the transfer of the work from the first to the second section. The right end of the carriage 40 as viewed in FIGURE 1 is provided with guideways which are effective continuations of the angle members 20 and 21. In a preferred form the guideways comprise an angle member 50 having an upstanding flange 50.1 aligned with the flange 22 of angle member 20, and a divided angle member 51, having upstanding flanges 51.1 in alignment with the flange 23 of the angle member 21. In order to support the work during its transfer from one work station to the next, the carriage 40 is equipped with pick-up bars extending transversely across the carriage. In view of the fact that these bars are essentially the same at each of the machine stations, and in each of the machine sections, description will be limited to that immediately to the right of the support member 14 in FIGURE 1. Each pick-up bar 52 is welded to the carriage rails 41 and 42 and is equipped with the positioning shoulders 53, 54, 55, which are located to accom modate the A, B, and C length doors. The carriage rails 41 and 42 are also equipped with positioning shoulders spaced apart suflieiently to engage the side Walls of the doors with an easy fit. These shoulders identified as 56, 56.1 and 57, 57.1 are duplicated at the several work stations at each of the machine sections. Pursuant to the above noted mention of nomenclature, the identi' cal elements in machine section 1a have the subscript a."

At the transverse station of section 1, the pickup bar 58 is essentially only to offer additional support for the small size B doors during the actual transfer of the door from the first to the second machine section and is devoid of the positioning shoulders to permit the door to slide freely along the pickup bar.

The first work section 3a of section la is provided with a hydraulic transfer mechanism by means of which a door carried by the guideways 50 and 51 is transferred from station 6 of machine section 1, to the first work station of the machine section In. As indicated in FIG- URES l and 2 the opposed standards 59, 59.1 support the parallel bars 60 along which ride the tubular runners of a framework 61 which includes a push bar 63 engageable with a transverse wall of a door as later described. A piston rod 64 fixed to the framework 61 is operatively associated with the hydraulic cylinder 65 which is rigidly supported at standard 59. The arrangement and stroke of the hydraulic cylinder 65 is such that the cylinder will etfect the transfer of the smallest size door B to the proper operating position on table 12a at which location a flame-annealing operation will be carried out by means of thegas head 28a. It will be noted in FIGURE 1 that at station 3a there is a work support 66 having the support shoulders 67 and 68 as necessary to accommodate the full length and the intermediate length doors. The support 66 is mounted on a pedestal 70 which as presently described passes through the gap between the aligned angle members comprising the guideway 51 during the transfer operation.

The transfer of the work from station to station an from machine section 1 to section 1a, is accomplished by the co-ordinated operation of the respective elevators 33 and 33a and the carriages 40 and 40a. The lift of the carriages by the associated elevators causes the respective pick up arms and rails of the carriages to raise the work from the several work tables and work supports, and from the transfer station 6 and work support 24 as indicated in FIGURE 3. It will be understood that during the period of work on the doors at their respective stations, the rails and the pick-up bars of the carriages are below the level of the tables and the work supports.

With respect to the transfer station 6 at the right end of machine section 1, the lifting of the carriage causes the work to be raised by the guideways 50 and 51. The rightward movement of the carriage of machine section 1 brings the work over transfer station 3a at the left end of machine section 1a, it being remembered that carriage 40a, being synchronized with carriage 40, has also moved to the right. Station 3a is illustrated as a combination transfer and work station, as a matter of convenient representation. As the movement of the carriage will be completed a substantial period of time before the elevator is actuated in a lowering direction, the carriage remains stationary in its elevated position over the machine section 1a. During this interval, the action of the hydraulic cylinder 65 causes its piston rod 64 and associated pusher to move the door transversely along the guideways 50 and S1 and the flat bar 58 until the end wall of the door strikes a valve actuating mechanism 93 (FIGURES 1 and 3) which interrupts the hydraulic pressure in the cylinder 65 and reverses the travel of the piston (not shown) to tion in readiness for the next operation, all as later described. The elevators then lower the carriages 40 and 40a whereupon each of the doors carried thereby is placed in its new operating station at machine section 1 or let. The carriage shift actuators are then energized to move the carriages in a leftward direction to position operation. During this 40 of machine section 1, the split guide rails them in readiness for the next leftward movement of carriage the standard 70 passes freely between 51 of the transfer station 6.

It will be understood that machine section 1a termi-- nates in an unloading station (not shown) at which operators remove the doors which at that time have had all of the operations performed thereon. Figure 4 schematically represents the hydraulic system for machine section In, it being understood that with the exception of the transfer cylinder 65, which is only at machine section In, the hydraulic system is duplicated at machine section 1. The pump P and receiver R constitute means for generating continuous hydraulic pressure. By way of pressure piping 72, and various normally closed solenoid valves later identified, the hydraulic cylinders 34a, 44a, and 65 are arranged to be supplied with pressure fluid selectively at each of their ends. By way of return piping 73, and normally closed solenoid valves later identilied, the pressure fluid may be caused to return from the respective cylinders to the receiver R of the pumping system. For cylinder 34a, a solenoid valve 74 controls the admission of fluid under pressure below the piston to eifect the lifting of the elevator 33a, and a solenoid valve 75 controls the admission of fluid under pressure above the piston to eifect a positive and controlled return of the elevator 33a to its home position. The opening of the solenoid valve 76 provides for the return of the fluid to the receiver during the up-stroke of the piston, and the opening of the solenoid valve 77 provides for the return of the fluid to the cylinder during the down-stroke of the piston. At cylinder 44a, a normally closed solenoid valve 80 controls the admission of pressure fluid to the left of the piston to enforce a rightward movement of the carriage 40a, and a normally closed solenoid valve 81 controls the admission of pressure fluid to the right of return the piston to a home posithe piston to enforce a leftward or return movement 0 the carriage. To provide for the release of the fluid contents of the cylinder during such operations, the normally closed solenoid valves 82 and 83 provided in the return line system 73, are operated to open position. Also, at cylinder 65, the normally closed solenoid valves 84 and 85 may be actuated to selectively admit pressure fluid to the cylinder to eifect the projection and return of the pusher 63; and for the obvious purpose of relieving the cylinder during such operations, the normally closed solenoid valves 86 and 87 are provided in the return line system 73 and are opened at the appropriate intervals.

FIGURE 5 represe ts a cam and switch chart for a conventional time-cycle switch (not shown) which controls the operations of the several solenoid valves for the cylinders 34a and 44a. It will be understood that because the cylinders 34 and 44 of machine section 1 are co-ordinated with their mac e section In counterparts for operations therewith, said machine section 1 has an identical hydraulic system and valves similar in arrangement and function to the valves previously enumerated. An independent time-cycle controller may be provided for each of the hydraulic systems; or the respective valves for the system of machine section 1 may be connected in electrical parallel with their counterpart valves, above enumerated, whereupon a single time-cycle controller may be employed.

Assuming now that the receiving station of machine section 1 is occupied and the elevator 33 and the shift carriage 40 (and their duplicates 33a and 40a of section 1a) are in their home position, the operator initiates the manufacturing process by closing a master switch (not shown) which energizes the time-cycle control and the mechanism of the several work stations which operate under their own control devices (not shown). At the completion of the time necessary normally to effect the work function, cams C1 and C2 close their associated switches S1 and S2, whereupon by way of the obvious circuit, solenoid valve 74 is energized to open and admit pressure fluid below the piston of cylinder 34, and solenoid valve 76 is opened to relieve the cylinder, as aforesaid. The closing of the valves upon the return of the switches S1 and S2 to open circuit position maintains the elevators in lifted position to permit the carriages 40 and 40a to shift. The carriages 40 and 40a occupy a raised position in which their various pick-up bars are substantially above the level of the respective work tables 7, 12, 15, etc., and the work support bars 11, 14, 16, etc. At such a level, the door A can be moved to the location of the first work station 3 without interference. In timed relation to the completion of the lift, cams C3 and C4 effect the closure of switches S3 and S4, whereupon solenoid valves 80 and 82 are energized to open position to effect a rightward movement of the carriage 40. The; movement of the carriage 40 transports the door A to the location of the first work station 3. The return of the switches S3 and S4 to open-circuit position causes the closure of the valves 80 and 82, whereupon the carriage remains in its rightward, elevated position. This interval of inactivity of the carriage is allocated to the operation of the transfer mechanism.

As the carriage 40 moves to the position in which the. transfer station 6 thereof is disposed above the work station 3a of machine section 1a, a bumper 88 on the carriage rail 41 engages the actuating mechanism of a normally open, double pole, single throw switch 90, (FIG- URE 6) to close the contacts of its switch stack, whereupon solenoids 84 and 86 are energized to open position by way of switch contacts 90 and the normally closed contacts 91 and 92 of a switch 93 which establishes the limit of travel of the pusher 63. Switch 93 is positioned on machine section 1a to be contacted by the pusher 63 if, as in the present situation, there was no door being transferred, or by the transverse wall moved by the pusher 63. As the pusher engages the of any door being actuator of switch 93, it effects the opening of switch s 91 and 92, whereupon the Solenoid valves 84 and 86 will return to closed position despite the fact that the contacts at switch 90 remain closed. The actuation of switch 93 will close the contacts 94 and 95 of said switch, whereupon the normally closed solenoid valves 85 and 87 will open to effect the return travel of the transfer mechanism. It is obvious that the carriage 40 must stay in its transfer position for the length of timenecessary to transfer the B size of the refrigerator doors, and that this time may be a second or two longer than that required to transfer the A size door. It isalso obvious that if no door were being transferred, the immediate disengagement of the pusher 63 from the switch 93 would cause the switch contacts 94 and 95 quickly to be opened (and contacts 91 and 92 closed) before the carriage 40 withdrew to the left to reopen the contacts of switch 90. A false operation of the hydraulic transfer system could result. The switch 92 is, therefor provided with any conventional dashpot or delay device 96 to maintain the switches 94 and 95 closed and the switches 91 and 92 open for the necessary period. The next operation is to lower the carriages 40 and 40a. This is accomplished at cams C and C6, which effect the opening of solenoid valves 75 and 77 to actuate the hydraulic cylinder 34 to its home position. When this is completed, the cams C7 and C8 close the switches S7 and S8 to effect the opening of valves 81 and 83 to return the carriage 40 in its leftward movement.

Because the door structures were deposited at the next successive work station upon the lowering of the carriage 40, the actual work period at the several work stations can commence as soon as the respective carriages lower to the extent necessary to position the door structure or structures at the next work station for it is obvious that the leftward movement of the carriage could not interfere with the work being performed on the Structures. The co-ordinated movement of the carriages 40 and 40a permits the rightward travel of carriage 40 without interference. The transfer angle members 51 pass over the support bar 66, whereupon as the carriage is lowered to deposit the door at the work station 3a, the members 51 and 58 of the transfer station straddle the support bar 66, and on the leftward movement of the carriage, the pedestal 70 will pass through the space provided in the transfer rail 51.

By the method and apparatus hereinabove described, a succession of doors of uniform or mixed length are worked on serially to accomplish all of the necessary operations at a first hinge position and then are transferred to the precise extent needed to bring their second hinge positions in proper operative relationship to a series of work stations to provide work thereon.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

We claim:

1. Apparatus for performing mechanical operations, respectively, at first and second work areas on a succession of structures in which the spacing between the respective work areas may Vary in any of said succession of structures, comprising a first mechanism having a series of work stations in rectilinear alignment relative to a first reference point on said structures, means at each of these stations for performing a mechanical operation on said structures only at the first of said work areas, a transfer station terminating said series of stations, a second mechanism having a receiving station and a series of work stations in rectilinear alignment relative to a second reference point on said structures, means at each of the work stations of said second mechanism to perform a mechanical operation on said structures only at the second of said work areas, means at the first mechanism for periodically advancing said structures from one to the other of said work stations and to said transfer station, means for aligning said transfer station with the receiving station of the second mechanism, a transfer mechanism disposed in operative alignment with said receiving station, means responsive to the alignment of said transfer station with said receiving station to energize said transfer mechanism for engagement with the structure on said transfer station and transfer of said structure into predetermined position at said second mechanism, means responsive to the attainment by said structure of said predetermined position to disengage said transfer mechanism from said structure and return said transfer mechanism in prepara tion for subsequent operation thereof, and means for serially advancing structures from one to another of said second mechanism work stations to complete the desired operations at the said second work areas of said structures.

2. Apparatus for performing mechanical operations, respectively, at first and second work areas on a succession of structures in which the spacing between the respective work areas may vary in any of said succession of structures, comprising a first mechanism having a series of work stations, means at each of these stations for performing a mechanical operation on said structures only at the first of said work areas, a transfer station terminating said series of stations, a second mechanism having a receiving station and a series of work stations in parallel but laterally offset relation to the said stations of the first mechanism, means at each of the work stations of said second mechanism to perform a mechanical operation on said structures only at the second of said work areas, means at the first mechanism for periodically advancing said structure from one to the other of said work stations and to said transfer station, said means including means for aligning said transfer station with the receiving station of the second mechanism, a reciprocable transfer mechanism at said receiving station, means responsive to the alignment of said transfer and receiving stations to energize said transfer mechanism to engage a structure on said transfer station and propel the same into predetermined position at a first work station of said second mechanism, means at said work station to reverse the transfer mechanism for disengagement from said structure and return to initial position preparatory to the next transfer operation, and means for serially advancing each structure from one to another of the work stations of said second mechanism whereby the desired operations may be completed at the second work areas of said structures, the means for effecting the periodic advancement of the structures at each of said mechanisms being coordinated for synchronized operation.

3. Apparatus for performing mechanical operations at first and second locations on a common wall of structures in which said locations have a fixed relation to said wall but in which in successive structures the spacing between said locations may differ, comprising a first conveyor mechanism, means for supporting said structures in serial relation on said conveyor mechanism with their respective first wall portions along a single line of movement parallel to the movement of the conveyor mechanism, means adjacent said conveyor mechanism establishing a first line of work stations at each of which work is performed only at the first location on said structure wall, means for effecting movement of said conveyor to conduct said structure from station to station, a second conveyor mechanism, means adjacent said second conveyor mechanism establishing a second line of operating stations at each of which work is performed only at the second location on said structure wall, the respective first and second lines of work stations being in parallel relation and spaced apart greater than the maximum distance between the said first and second location in any structure to be worked upon in said apparatus, means on said first conveyor to successively position each said structure with the second wall location thereof in a predetermined operative relation to the said second line of operati rig stations, means including a ram engageable with said structure to effect the transfer thereof from the first to the second of said conveyors, means responsive to the positioning of said structure in said last named operative relation to initiate the operation of the ram, and means for operating said second conveyor to move the structures thereon from one to the other of said operating stations of the second line.

4. Apparatus for performing mechanical operations at first and second work areas of a succession of structures in which the spacing between said work areas may differ in any of said succession of structures, comprising mechanism establishing a first series of work stations specific to the first of said work areas, means for relating said first series of work stations to a fixed reference point common to said structures, mechanism establishing a second series of work stations specific to the second of said work areas, means for relating said second series of work stations to a fixed reference point common to said structures, means at each of the respective work stations for performing a desired mechanical operation on said structures, means for conducting said succession of structures in step-by-step fashion from one to the next of said first series of work stations while maintaining the relationship between said work stations and said reference point, means automatically effective upon the completion of the operation at the last of said series of first work stations to establish each of the structures, in succession, in desired relationhip of the second of said series of work stations to the said fixed reference point, and means for conducting said succession of work stations in step-by-step fashion from one to the next of said second series of work stations while maintaining the relationship between said second series of work stations and said reference point.

5. The method of manufacturing refrigerator cabinets or the like in which work operations are to be performed on first and second work areas of each of a succession of cabinets. which includes the steps of selecting for each of the cabinets of the series commonly oriented first and second referencee points which bear a fixed relation to the respective first and second work areas regardless of a variation in spacing between said reference points which may exist in one cabinet relative to another in the series, moving said cabinets serially from one to another of a first series of work stations while maintaining a fixed space relationship between the first reference point of each cabinet and said work stations, performing at the respective work stations work operations on said cabinets only at the first work areas thereof, transferring said cabinets serially from the last of said first series of work stations to the first of a second series of work stations, moving said cabinets serially from one to another of said 10 second series of work stations while maintaining a fixed space relationship between the second reference point of each cabinet and said second work stations, and performing at the respective second work stations work operations on said cabinets only at the second work areas thereof.

6. Apparatus for manufacturing refrigerator cabinets or the like in which work operations are to be performed on first and second work areas of a succession of cabinets in which the respective work areas are uniformly related to first and second reference points common to all cabinets but in which the spacing between said reference points may vary in successive cabinets, comprising a first machine section having a series of work stations spaced one from the other in single file and a transfer station following said work stations, work devices at each of said work stations to perform work operations on the first area, only, of said cabinets, a reciprocating conveyor having a fixed forward travel for depositing the cabinets serially at the successive work stations and the transfer station, support arms on said conveyor to reassembly secure the cabinets thereon with the stud said first reference point in fixed space relation to (the work devices at the respective stations, support members at said stations to accept the cabinets from said conveyor while maintaining said space relationship; a second machine section disposed parallel to but in laterally offset relation with said first machine section, said second section having a receiving station and a series of work stations spaced one from the other, said receiving station being related to the first machine section whereby the conveyor of the first section will move a cabinet from its transfer station to said receiving station following each forward travel of the conveyor, work devices at each of said second work stations to perform Work operations on said cabinets at the second area, only, thereof, a shift mechanism disposed adjacent to said receiving station for moving a cabinet from said receiving station to the first work station of the second machine station with the second reference point of said cabinet in predetermined operative relation to the work device at said station, means responsive to the receipt of a cabinet at said receiving station to energize said shift mechanism to effect said cabinet movement, means responsive to the receipt of said cabinet at said first work station to return said shift mechanism to home position, and conveyor means on said second machine section to deposit said cabinets serially at the successive work stations of the second machine section while maintaining a desired relationship of the second reference points to the work devices at said work stations.

References Cited in the file of this patent UNITED STATES PATENTS 2,923,952 Sawdey Feb. 9, 1960 

